I am very interested in the Rtrak for our Civil Air Patrol
squadron, but it does not appear to meet NTIA specs, at least as far
as I can tell from this note from Juergen that I don't fully
understand. Can you interpret and tell us if there is a way it can be
made to meet specs?
"The SRB-MX146 meets the spurious emission requirement but for
harmonics you will need an external low pass filter to meet the
-70dBc. On it's own it is -45dBc (usually quite a bit better).
Stability on the parts we measured would meet the ±2.5ppm but we
spec it at ±5ppm as we don't want to temperature test each and every
unit. The digital injection modulation requires a reference oscillator
with sufficient tuning range. These are not as stable as we would like
them to be and the remaining temperature drift is compensated with the
on-board thermometer. This can be set extremely accurate but as the
crystal oscillators vary it isn't a guarantee to always be within your
limits, we only have a fixed compensation curve.